Another limit was the number of subjects lost during follow-up that could introduce a non differential bias of classification and overestimate the relative risks.
If, however, there was a bias in classification of cause of death in favour of the treated group, fewer deaths would be ascribed to fungal infection and more deaths to other causes in this group.
This might cause a bias in the classification of tumor types.
In conclusion, our findings suggest that several data analysis pitfalls of [8] led researchers to identify SNPs that are not statistically significant and to derive a severely biased estimate of classification performance of esophageal cancer patients and healthy controls on the basis of these SNPs.
On the other hand, if the performance is assessed using the very same data that are used for developing the classifier, this obviously leads to a biased down estimate of classification error.
We observed that read speech was better recognizable than spontaneous speech (see Fig. 17), which we believe is partially a result of classification bias, but also a result of the higher diversity of spontaneous speech class examples.
Second, self-reporting of measures presented a risk of classification bias.
The decision function of SVM is listed as follows: (7) h (x ) = sgn (∑ i = 1 sv α i y i K (x, x i ) + b ), where sv represents the number of support vectors, α i is the Lagrange multiplier, b is the bias of optimum classification hyperplane, and K x, x i ) denotes the kernel function.
The second reason, psychosis is a continuum and the demarcation between cases currently used in psychiatry is a bias because of its dependence on categorical classification without any relation to any biological etiology.
Note that an improvement of classification accuracy by bias adaptation was highly significant for two subjects.
